NowThis Developer Docs

Privacy-first, self-hosted CalDAV task manager for iOS.

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Welcome to the open-source documentation for NowThis.

This site provides technical guidance for developers looking to build, fork, or contribute to the NowThis iOS client.

What’s New in 1.0.4

The 1.0.4 release focuses on faster task entry, rock-solid Nextcloud sync, and smarter due dates.

• Add tasks by voice — Natural-language quick-add via Siri: dictate one sentence (“buy milk tomorrow at 5pm”) and NowThis parses the title and due date/time. The same parser powers typed Quick Add.
• Faster task entry — Single-tap to add on any list, an inline quick-add field on every list, and smart new-task defaults (app-wide and per-list default due date and time).
• Reliable two-way Nextcloud sync — Server-side creates, edits, completions, and reorders now reach the device and widget automatically; manual ordering round-trips via X-APPLE-SORT-ORDER; subtasks sort and reorder under their parent; fresh installs sync the last 3 months of completed tasks by default.
• Smarter due dates — Every due date shows a time slot (all-day tasks read “· All day”), all-day (date-only) due dates now show the correct day, and an All Day toggle flips a task between all-day and a specific time.
• Clearer sync errors — Plain-language banners for sign-in, connection, permission, and temporary server problems.
• Stability — The Kanban board no longer crashes when a task is deleted during sync.

Core Architecture

NowThis is written in Swift 6 using SwiftUI for the user interface and SwiftData for local persistence.

Key technical pillars include:

• CalDAV Sync Engine: A custom-built, actor-isolated sync engine (CalDAVClient) that supports background fetching and ETag-based inbound change detection with conflict resolution.
• Natural-Language Parsing: A shared NaturalLanguageParser turns free-text and Siri dictation into structured title + due date/time, powering both Quick Add and App Intents.
• Local Vault: A completely offline mode that bypasses the network layer, storing everything securely on-device.
• Geofencing: Location-based task reminders driven by CoreLocation and UserNotifications.
• App Groups: Shared state between the main app and widgets using iOS App Groups.

Getting Started

NowThis uses XcodeGen to avoid merge conflicts in .xcodeproj files. To build the project locally:

1. Clone the repo from GitHub.
2. Create a Local.xcconfig file from the template and add your Apple Developer Team ID.
3. Run xcodegen generate to create the .xcodeproj file.
4. Open the project in Xcode and run.

Sync Deep Dive

Our sync engine communicates with any standard CalDAV server (with first-class support for Nextcloud). It uses a pull-then-push strategy:

1. Fetch latest changes via REPORT requests.
2. Resolve conflicts using ETag matching.
3. Push local changes via PUT requests.
4. Refresh the local SwiftData ModelContext.

Security & Privacy

We take privacy seriously.

• No analytics SDKs or tracking frameworks are included.
• All credentials are stored in the Secure Enclave using kSecAttrAccessibleAfterFirstUnlockThisDeviceOnly.
• Network requests are strictly authenticated and validate redirects to prevent token leakage.

License

NowThis is released under the GNU General Public License v3.0 (GPLv3). For more details, see the LICENSE file in the repository.